Next, we head into the heart of two dangerous countries in the middle east. Iran and syria. Two countries on a hair trigger, with powerful consequences for the united states. Our correspondents are nationed in both hot spots tonight, and in iran, they continue to enrich uranium for nuclear purposes. Does this mean nuclear weapons? Can they be stopped? Abc's david muir leads us off. He is there on the eve of the crucial talks. Good evening, david. Reporter: Diane, good evening. We are coming to you live from tehran tonight. Iran has allowed us in at this critical moment. The u.S. And much of the west convinced that iran continues to work toward those nuclear weapons. Iran, of course, denying this and, as you point out, we are just days away now from the u.S. And iran joining a small group of others as they return to the negotiating table. We landed in iran, in a country where american journalists are rarely allowed to visit. Rarer still, we were given access to the people, the streets of tehran. Above ground, a bustling city of 12 million. Below ground, we discover a gleaming subway system, far quieter and cleaner than the famous subways of new york city. And there was something else very different. This says "women only" right here. The back of the train, reserved for women. But beyond the trains, the traffic, everywhere you look, there is something else on the move here. The prices. Skyrocketing inflation. Their currency losing 80% of its value in just the last year. U.S.-Led sanctions tying an economic noose around iran. It's being felt by this young woman and her mother. Day to day, increasing prices. Reporter: You see it day to day? Yes. I think it's a lot of pressure to the people. Reporter: The iranian people. Iranian people. Most of them, the normal people. Reporter: The relationship between the u.S. And iran never recovered after those 444 days, americans held hostage as the world watched. Right here in the heart of downtown tehran, what used to be the u.S. Embassy. Of course, the infamous backdrop of the hostage crisis that began g in '79. You can see the gates still here, still closed decades later, and behind us here, what used to be the seal. You can sill faintly make out united states of america. Still today, the walls here painted with anti-american murals, the guard stations empty. And tonight, many here are hoping for an end to the sanctions, to the nuclear standoff. We hope. We hope. Reporter: You hope it ends? Better days. Reporter: Meantime tonight, one of iran's closest allies, syria, also being watched by the world. As conditions quickly detier area rate, as a assad struggles to hold onto power. Abc's terry morgan is in damacus. Reporter: David, less than a mile from here, just over there, there's another hotel, a small place, where visiting sports teams will stay. It's just near the stadium. This afternoon, the war came there. A rebel mortar shell fired from the suburbs blasted out windows and scattered shrapnel into the buding, killing a young soccer player. Soccer player. "My friend was in front of me and he died," he tells me. "We are all just athletes," he says. "We have nothing to do with this violence." In hamouriyah, a suburb just a few miles away from the hostel, at least 13 people were killed in an apparent government airstrike. And a rebel group released this video today, which they claim shows them shooting down a syrian jet fighter. This afternoon, we went to the main military hospital in damascus. Syrian forces are taking heavy casualties in this war, as many as 16,000 killed. This general, his legs badly shot up, his spirit defiant. I ask him about the allegations that his troops are massacring civilians. "This is a false accusation," he tells me, "and had it come down to me, I would have adopted a scorched earth policy with these armed men." But life somehow goes on here. You can still stroll through the old market. We bought nuts from a very enthusiastic merchant. And you can still enter the splendid ummayad mosque at dusk, an ancient house of god, an oasis of peace, where the people pray and the children play on an endless carpet, while, outside, their nation drowns in the blood of civil war. Terry more wran ran, abc news,

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